more confused than ever (degreeing a cam)

-
V

volaredon

Well-Known Member
Joined
Feb 28, 2010
Messages
4,305
Reaction score
2,461
Location
IL
Ive searched on here, looked at several You tubes etc. Wasnt sure whether to tie onto one of the old threads or start another. Thought starting another would be easier. Maybe less confusing.
I havent done anything with my motor in a while (74 225 being built to go into 85 D150)
819 Oregon cam
Im gonna copy/paste from another thread here, the specs for this cam
Since I aint great with computer stuff (It would be easier to scan the sheet in instead of copying it manually for sure) here goes...
see if you guys can make sense of things I can't...
Lobe Separation 110 Lobe Center Line Int 106 Exhaust 114
how can lobe centerline and Lobe Separation "not" be the same as each other? 1st thing that doesn't make sense.
Cam lobe Lift .291 on both intake and exhaust.

Duration at 0.002 318 both Intake and Exhaust
at 0.006 289 both
at 0.012 ("0.012" "penciled in") 264 both
at 0.020 248
at 0.026" 240
at 0.050 219
at 0.100 187
at .200 125

Valve Clearance 0.012" both
Checking tappet Dia 0.904" Tappet type Mech Flat
Cam timing @0.050" tappet rise OPEN CLOSE
INTAKE 4* BTDC 36* ABDC
EXHAUST 44* BBDC -5* ATDC

and most of these numbers are nowhere close to what Im seeing.
I've established the 106,* wondering why I ain't seeing the 110* instead.
Also not at the degree wheel numbers I was expecting to see them at.

I have verified the degree wheel TDC position, by both dial indicator and by piston stop. Several times. Its dead nuts.

I have one of those "Proform" dial indicators that slips right into the lifter hole, reads straight off the cam. the body of it could be a little longer, it's not long enough for the whole gauge to protrude above the block deck. The nub on back of it hits the block, when the body is seated in lifter hole. This is with dial indicator pulled out as far as it can be, and still be held by the setscrew in the body.
I have a (I think it's a COMP brand) 0-180-0 degree wheel, piggybacked onto a COMP 1/2" drive crank socket, with the big knurled nut.

I have Cloyes double roller sprockets (rumored to have been old Mopar Performance stock) and a MP double roller chain. Set dot to dot.

I haven't put the head on yet.

seeing the cam open to 0.050 at 62* and 150*. add, divide and I get my 106* which is what the "installed centerline" is supposed to be.
sheet says "CAM TIMING AT 0.050" TAPPET RISE;
at 4* BTDC and close at 36 ABDC, I'm not seeing anywhere near those numbers. this is where Im getting the 62 and 150.
this is where the confusion starts.

And YES I am using the 2nd lifter hole from the front, which is the #1 intake lifter hole to make the measurements.
I want to do this once and do it right, This is where I usually throw my hands up and say "screw it" and continue assembly and hope for the best. But I aint wanting to do that no more.
I think I remember degreeing a 318 once (out of the 5-6 Ive done up over the years) successfully years ago. but wont swear to that either.
 
Last edited:
Because the cam is being installed with 4deg advance, which is most likely ground in, so install the timing set w/-0-advance & check. Intake is recommended to be 106deg ATDC, which would put the exh at 114deg BTDC.
Maybe Your confusion lies in that LSA is given in CAMSHAFT degrees, & the centerlines are in CRANKSHAFT degrees..which is obviously 2X cam deg.
 
Last edited:
Lobe separation is the angle between the intake and exhaust lobes that Is ground into the camshaft during manufacture. Installed centerline is wherever YOU put in in the engine. You can install the centerline at 95, or 118, or whatever. Cam maker recommends 106.
 
You need to buy the Comp Cams video. That way, you can back it up as many times as necessary to get it clear in your mind. It's not difficult at all to do once you've done it a few times.
 
Unless I intentionally install it a tooth off "straight up" (dot to dot" ) is my only choice with this setup. I don't have multiple keyways.
What I don't get is where on the degree wheel I am seeing the 0.050 on either side of max lift. Where do the 62 and 150 come from Instead of the 4 and 36 that the spec sheet is saying?
I have the degree wheel on the crank, (not on the cam)
I realize it has to go twice for each round of the cam.
 
Last edited:
I understand what the lobe center line is. And that it is ground in. But installing it at 106 instead of the 110 won't that mean it really isn't centered, being ground on 110?
I've had the head loosely set onto the block with 2 head bolts run most of the way down, less than finger tight with a garbage bag over the engine stand,// this is all I have left, and I can bolt the head on, put the timing cover on and actually seal this motor up so no crap can float in.
 
volaredon said:
Unless I intentionally install it a tooth off "straight up" (dot to dot" ) is my only choice with this setup. I don't have multiple keyways.
What I don't get is where on the degree wheel I am seeing the 0.050 on either side of max lift. Where do the 62 and 150 come from Instead of the 4 and 36 that the spec sheet is saying?
I have the degree wheel on the crank, (not on the cam)
I realize it has to go twice for each round of the cam.
Click to expand...
I'm not bein smartass here when I ask this, so don't take it that way, ok? But if you only have one keyway and can only install it dot to dot, what difference does "all that" make? Just install it and go.

....now, unless you're thinkin about getting a set where you can actually DEGREE it instead of just slap it in, then that's different.
 
So if you are not using multiple keyway crank gear, then how are you planning on making any changes to cam timing ? Are you able to change top gear relationship on slants (offset dowels, etc ??). Can't remember how they are set up.
 
65wgn440 said:
So if you are not using multiple keyway crank gear, then how are you planning on making any changes to cam timing ? Are you able to change top gear relationship on slants (offset dowels, etc ??). Can't remember how they are set up.
Click to expand...
No.
 
my68barracuda said:
I use off set bushings to set the cam timing on the slants that I build.
You have to drill the dowel pin hole in the cam gear over size so it accepts the bushings. IIRC the bushing kits come in 2, 4, 6 and 0 degree off sets.
Click to expand...
Yup, that's an option for sure. I wish someone would make a timing set like that. IMO, that's a lot easier than taking the crank gear off and puttin it back on.
 
RustyRatRod said:
Yup, that's an option for sure. I wish someone would make a timing set like that. IMO, that's a lot easier than taking the crank gear off and puttin it back on.
Click to expand...
Google ‘Mr Gasket Cam Bushing to advance or retard the cam’,,,
You should get pictures and multiple sellers.
 
A couple of comments.
- off set bushings. Isky makes them, # OFB-0-2-4-6-8
- moving a tooth is likely to change the cam position faaaaaar more than 4 crank degrees.
- millions of engines, slant 6s some of them, had cams installed at the factory without any type of dialling in. And they all ran fine. If this was my engine, I would install the cam & drive the car. If you are happy with the performance, job done. If not happy, then you could look at adv or ret the cam depending on what you want to change.
 
When I degreed the cam on the slant I recently put together, I had a multiple keyway gear that got me close. I still needed an additional 4* so my machine shop gave me some cam bushings to fiddle with. For what it's worth, he said they were for a Chevy but they are the same for a slant. The did fit and work just fine.
 
volaredon said:
I understand what the lobe center line is. And that it is ground in. But installing it at 106 instead of the 110 won't that mean it really isn't centered, being ground on 110?
I've had the head loosely set onto the block with 2 head bolts run most of the way down, less than finger tight with a garbage bag over the engine stand,// this is all I have left, and I can bolt the head on, put the timing cover on and actually seal this motor up so no crap can float in.
Click to expand...
It's NOT SUPPOSED TO CENTER AT 110deg, that is "straight-up". For best performance it is ground & designed to have the overlap crossover point advanced 4deg BTDC.
 
volaredon said:
Ive searched on here, looked at several You tubes etc. Wasnt sure whether to tie onto one of the old threads or start another. Thought starting another would be easier. Maybe less confusing.
I havent done anything with my motor in a while (74 225 being built to go into 85 D150)
819 Oregon cam
Im gonna copy/paste from another thread here, the specs for this cam
Since I aint great with computer stuff (It would be easier to scan the sheet in instead of copying it manually for sure) here goes...
see if you guys can make sense of things I can't...
Lobe Separation 110 Lobe Center Line Int 106 Exhaust 114
how can lobe centerline and Lobe Separation "not" be the same as each other? 1st thing that doesn't make sense.
Cam lobe Lift .291 on both intake and exhaust.

Duration at 0.002 318 both Intake and Exhaust
at 0.006 289 both
at 0.012 ("0.012" "penciled in") 264 both
at 0.020 248
at 0.026" 240
at 0.050 219
at 0.100 187
at .200 125

Valve Clearance 0.012" both
Checking tappet Dia 0.904" Tappet type Mech Flat
Cam timing @0.050" tappet rise OPEN CLOSE
INTAKE 4* BTDC 36* ABDC
EXHAUST 44* BBDC -5* ATDC

and most of these numbers are nowhere close to what Im seeing.
I've established the 106,* wondering why I ain't seeing the 110* instead.
Also not at the degree wheel numbers I was expecting to see them at.

I have verified the degree wheel TDC position, by both dial indicator and by piston stop. Several times. Its dead nuts.

I have one of those "Proform" dial indicators that slips right into the lifter hole, reads straight off the cam. the body of it could be a little longer, it's not long enough for the whole gauge to protrude above the block deck. The nub on back of it hits the block, when the body is seated in lifter hole. This is with dial indicator pulled out as far as it can be, and still be held by the setscrew in the body.
I have a (I think it's a COMP brand) 0-180-0 degree wheel, piggybacked onto a COMP 1/2" drive crank socket, with the big knurled nut.

I have Cloyes double roller sprockets (rumored to have been old Mopar Performance stock) and a MP double roller chain. Set dot to dot.

I haven't put the head on yet.

seeing the cam open to 0.050 at 62* and 150*. add, divide and I get my 106* which is what the "installed centerline" is supposed to be.
sheet says "CAM TIMING AT 0.050" TAPPET RISE;
at 4* BTDC and close at 36 ABDC, I'm not seeing anywhere near those numbers. this is where Im getting the 62 and 150.
this is where the confusion starts.

And YES I am using the 2nd lifter hole from the front, which is the #1 intake lifter hole to make the measurements.
I want to do this once and do it right, This is where I usually throw my hands up and say "screw it" and continue assembly and hope for the best. But I aint wanting to do that no more.
I think I remember degreeing a 318 once (out of the 5-6 Ive done up over the years) successfully years ago. but wont swear to that either.
Click to expand...
A couple of ideas on degreeing a cam:
1) I have only one piston / rod assembly in as that puts much less drag on rotating the crank and I think that gives me better precision. Put some light oil in the cylinder bore to reduce friction.
2) some degree wheels are easier to read than others, just the way they are marked. A larger diameter wheel is much easier to read.
3) there are two different methods used to degree a cam. One allows you to actually see the valve opening and closing marks the other gives the intake centerline. Each has its own sequence for checking. Understand how they are different and don’t mix or confuse the two methods. I use the Intake Centerline method, but then go back and check the actual valve opening and closing points, because I am a nerd about things like that.
4) the set up of the dial indicator is critical. The push against the indicator’s stem needs to be absolutely straight and not at an angle so travel is not lost sliding across the indicator stem, but pushes on it directly. The set up must be flex and shift free. Once zeroed, the indicator must return to zero after the crank is spun 360 degrees. Do the 360 crank spin several times. The indicator must return to zero each time. Likewise the wheel and pointer must show actual TDC on each of several test full spins of the crank.
5)remember that dot to dot on a slant, meaning that the cam gear dot is at 6:00 and the crank gear dot is at 12:00 has the #1 and #6 pistons at TDC, but it is the #6 cylinder that has both valves closed and is in the firing position.
You will need to spin the crank around twice again watching the indicator on the intake valve to see the #1 intake open then close. That puts the #1 cylinder in the firing position.
6) test your cam degree method against the cam card. You should be able to get exactly or at worst very close what the cam card says, and the values read should repeat doing multiple spins of the crank.
 
Last edited:
If your cam was ground and installed straight up the Intake Centerline, or the point in crank degrees where the intake valve would be at max lift would be with the piston 110 crank degrees ATDC.
With four degrees of advance ground into the cam the ICL is 106 meaning that the intake valve is at max lift with the piston 106 crank degrees ATDC.
As the duration on a cam is fixed, that means the intake valve is starting to open earlier, and then also closes earlier with an ICL of 106 vs 110. An earlier opening and closing intake valve helps low end torque.
An Intake Centerline of 106 is ok for a slant, but it can go a bit lower. To do that you can use the cam gear bushings mentioned earlier. I set the cam in the D150 at 102 ICL. Keep in mind that you will not feel a dramatic difference between a 102 and a 106, you could see it on a torque curve on a dyno or on a drag strip with a well tuned vehicle, but it is not a day and night difference daily driving on the street. But then the engine building-tuning is all about optimizing the motor. It will never be easier than now to advance the cam a bit more. Assuming the dynamic compression can handle the bump up.
Concerning the valve event timing. You chose .050 ahead and after peak lift to find the Intake Centerline, but you could have used .100 or .075 or about anything else as long as the two values split the lob peak. For valve event timing .050 is specific to the cam card’s stated valve lift at .050. I think you are confusing crank degree timing with .050 of valve lift.
To put it another way:
when figuring Intake Centerline you are measuring and the calculating from an equal distance either side if the intake lobe peak.
When verifying valve event timing you are measuring .050 up the ramp from the base circle on the cam lobe.
Basically the two different techniques measure from opposite sides of the cam profile. So the degree wheel is not in the same place relative to the pointer for Intake Centerline and valve event timing.
 
Last edited:
Personal observations:
1. Slant six offset cam sprocket bushings are the same as Chevy/BB Mopar. The sprocket needs to have the dowl pin hole drilled larger, to install the bushing. The bushings are sold in packs of "even" degrees, or "odd" degrees.
2. Some/most "stock" type cam sprockets, now have a "notch", instead of a "hole". You cannot install a offset bushing in these, unless you drill a hole in a different location.
3. Any one that spends money to buy a new cam, and doesn't degree it in, has wasted their money. I have had all new parts, (except for the crankshaft) and had to "jump" the sprocket one tooth, then use the bushing to get the cam at the correct centerline. That's how far the cam was off at "dot to dot". Tolerance stack up.
 
Yeah if this thing didn't come in where it's supposed to be I was gonna get a pack of the offset bushings and drill out the dowel hole in the cam gear, already figured on that.
I have watched several videos on you tube, and I feel I went thru the right motions, and many times at that.
And when I add the 2 numbers on the degree wheel, add them and divide them, I get the "106" that I think I am supposed to. It's the "where I get those numbers" on the degree wheel that are not making sense to me.
The degree wheel is marked with a range for intake and exhaust open and close range and all the numbers are each coming within the marked ranges as should be expected but not at the numbers on the spec sheet that came with. I have a ~16" wheel marked 0-180-0, not the one that started over every 90*
 
Last edited:
RustyRatRod said:
I'm not bein smartass here when I ask this, so don't take it that way, ok? But if you only have one keyway and can only install it dot to dot, what difference does "all that" make? Just install it and go.

....now, unless you're thinkin about getting a set where you can actually DEGREE it instead of just slap it in, then that's different.
Click to expand...
Wasn't trying to be a smartass, I figured it was a "don't know what parts I had at hand til I said so" deal.
And my cam gear doesn't have the long slot at the dowel pin location, just a hole. So I could drill it out and bush it. But with all the talk about dots being so far off I figured I'd better check it out.
What I have is all "old stock" parts. Nothing made in the last 25 years.
Like I've said elsewhere I've done several timing chains over the years, and I'm at the point of install where I have often said "screw it" and continued with build up in the past. And I'm not wanting to do that here.
I have the dutra book, and I did drill out the 1/8" hole in the cam gear across from the dowel pin location to keep oil pressure from building up behind the gear, as was listed in that book.
 
You want the intake, #1 lobe at 106 degrees, you are done unless the cam manufacturer wants you to install it at a different number. All the rest is on the cam manufacturer.
 
Wow. First off I only use cam centerline. That way I can be off a bit on the dial indicator positioning and still get accurate results. Most degree wheels, including the one I have, are set up for lift at some degree, they are not set up for using the centerline method. So I've remarked my wheel to allow me to use the centerline method without a lot of additional math. But IMHO, if you ever do use the centerline method, you'll never screw with the lift at some degree method. Just my opinion.
 
I use the cam centerline method, also, in most cases. There are a few cam grinds, that must be degreed using a different method, but the cam manufacturer will specify that. I do use the other numbers, just to verify the cam is the one I wanted. You can put the cam (any cam) in at 106 CL, but that doesn't mean the cam is the one you think you have. Using the intake open, and close numbers, will verify that. Example: Mopar .434 lift, installed at 103 center line, and the Mopar .528 also installed at 103 center line. Unless you check the other numbers, how do you know what cam you have.
 
And when I add the 2 numbers on the degree wheel, add them and divide them, I get the "106" that I think I am supposed to. It's the "where I get those numbers" on the degree wheel that are not making sense to me.

Don, If I am reading what you wrote correctly, I believe you are saying that you can get the 106 Intake Centerline, but you are not getting the Valve Event timing that makes sense. If so that is because you are not repositioning the timing disk to properly get and read the Valve Event timing.

The Intake Centerline has the dial indicator an equal distance from the highest lift point of the cam lob. You used .050 on either side of the max lift point of the cam, but you could have used .100 or .075 or .060 and after doing the addition and division got to the same 106 Intake Centerline.

The Valve Event timing has the dial indicator on the opening ramp of the cam where the valve is open .050 for the valve open reading and on the closing ramp of the cam where the valve is .050 from being closed. To match up with the .050 valve event timing on the cam card the indicator must be where the valve is open .050 and on the closing side the valve is .050 from being closed.

The Intake Centerline method measures with the indicator close to the max valve lift point of the cam.
The Valve Event timing method measures with the indicator close to the base circle of the cam.

To get the indicator in the correct position the indicator is not relocated, the cam and the crank with the degree wheel needs to move.
 
Last edited:
You must log in or register to reply here.
-

Back
Top